TOUGHNESS OF 12-PERCENT-CR FERRITIC MARTENSITIC STEEL WELDS PRODUCED BY NON-ARC WELDING PROCESSES/

Low carbon 12%Cr steels can offer reduced life cycle costs in many app lications. The present work examined the behavior of commercial steels of varying composition when subject to low heat input welding by the electron beam (EB) process and to a forge cycle by linear friction wel ding (LFW). Charpy impact testing was carried out on the high temperat ure heat-affected zone (HAZ)/ fusion boundary or weld interface, with metallographic examination. With EB welding, the ductile-brittle trans ition temperature (DBTT) was below 0 degrees C (32 degrees F) only for steel of low ferrite factor giving a fully martensitic weld area. Hig her ferrite factor alloys showed predominantly ferritic transformed mi crostructures and a transition well above room temperature. Grain coar sening was found even with low EB process power, the peak grain size i ncreasing with both heal input and steel ferrite factor. Use of LFW ga ve a fine weld area structure and DBTTs around 0 degrees C even in hig h ferrite factor (FF) material.